You sign in. Take a seat and they should call you shortly. If they don't you need to check with them. That is the registration part, then you sit back down and wait until they call your name. If they don't within a reasonable amount of time, then DEFINITELY go back up.
Just sign in and they will call your name
Just sign in they will call you sometimes immediately after you sign in
Just sign in. They will call you in a few minutes if not immediately for check in. Then you can tell why you are there.
Thanks! Your answer is awaiting moderation.